Illumination device having beam splitting polarization means

Abstract

A device for illuminating an area includes a circular reflector for focussing a light ray from a light source into a beam. A polarizer splits the beam into an effective beam having a first polarization direction and a complimentary beam having a second polarization direction. The polarizer reflects the effective radiation toward the area to be illuminated and transmits the complementary radiation to a rough surface having a roughness at least an order of magnitude greater than the wavelength of the light to diffuse the light and reflect at least a portion of the complementary beam back to the reflector and another portion to the area to be illuminated.

I claim: 
     
       1. A device for illuminating a rough surface area comprising: means for focussing a light ray from a first light source into a beam;   polarization means for splitting said beam into an effective beam having a first polarization direction and a complimentary beam having a second polarization direction, said polarization means reflecting said effective beam toward said rough surface and transmitting said complementary beam;   said rough surface having a roughness at least an order of magnitude greater than the wavelength of said light for diffusing and reflecting at least a portion of said complementary beam back to said means for focussing and for reflecting another portion to said area.   
     
     
       2. The device of claim 1 further including: second means for focussing light from a second light source into a second beam;   second polarization means for splitting said second beam into a second effective beam having said first polarization direction and a second complimentary beam having said second polarization direction, said second polarization means reflecting said effective beam toward said area and transmitting said second complementary radiation to said first light source;   a second rough surface having a roughness at least an order of magnitude greater than the wavelength of said light for diffusing and reflecting at least a portion of said first complementary beam to said first means for focussing; and   wherein said first and second rough surfaces are the surfaces of said first and second light sources.   
     
     
       3. The device of claim 2 further including means for alternately turning said first and second light sources on and off. 
     
     
       4. The device of claim 1 wherein said polarization means includes reflecting elements which are individually transparent to one of the primary colors of light and reflect light having wavelengths different from the primary light colors. 
     
     
       5. The device of claim 1 further including a sensor for sensing the intensity of light at said area; and control means responsive to said sensor for providing an alarm when said light intensity falls below a preselected level.   
     
     
       6. The device of claim 2 further including a sensor for sensing the intensity of light at said area; and control means responsive to said sensor for providing an alarm when said light intensity falls below a preselected level.   
     
     
       7. The device of claim 2 further including means for reflecting said complementary beam to said area as a beam parallel to said effective beam to illuminate a large area.